There exist many known accelerator agents and systems for the curing and vulcanization of rubber(s) of either the natural or synthetic variety (and mixtures thereof) which are compounded for that purpose. These include various and numerous sulfur-containing materials, as are all set forth in the VANDERBILT Rubber Handbook, in Current Edition, and which are known for such usage when employed individully or in combination with other materials.
Unfortunately, the great preponderance of satisfactory accelerator materials tend to be undesirably expensive. As is abundantly evident in the ensuing Specification, the accelerator ingredients employed in practice of the present invention are obtainable and providable by a relatively simple process utilizing generally readily available and relatively low cost starting raw materials.
The prior art in this particular area is of great magnitude. In fact, the basic fundamentals and operational principles and limitations of accelerators and curing agents for the vulcanization of rubber are so well known by those skilled in the art that further elaboration thereon is unnecessary for understanding of the advance possibilitated by and with the development of the present invention.
Although heretofore unknown accelerator materials in and for rubber compositions, various esters of phosphorodiothioic acid are recognized compositions of matter, as disclosed in U.S. Pat. No. 2,586,655.